This invention relates generally to specially configured prefabricated structural modules for employment in the construction of walls. More particularly this invention relates to that class of wall wherein the structural elements of the module form interior cavities or cells in which granular material is deposited. This enclosed granular material, through the action of friction against the generally upright walls of the cells, adds its own weight to that of the structural parts to form a more effective assembly.
The structural modules of the present invention are intended to be used in combination with other similar modules arranged in horizontal rows and, according to the height required of the structure, in additional superposed horizontal rows of modules each properly proportioned to provide adequate stability to the assembled structure.
More particularly the present invention relates to an improved prefabricated structural module of the general type shown in U.S. Pat. No. 3,877,236 and U.S. Pat. No. 4,372,091. These patents show structural modules which, when assembled in combination laterally and vertically to form a wall structure, create cellular cavities to contain fill material which acts in consort with the wall modules to form a gravity wall. The principal distinction between the referenced patents lies in the method utilized to transfer the lateral components of forces acting upon the walls.
In U.S. Pat. No. 3,877,236 the lateral forces are transmitted by interlocking contours located in the top and bottom surfaces of the face panels. This detail is effective for small to moderate lateral forces, but the stresses induced in relatively thin face panels by high lateral stresses in high structures cannot be economically resisted by these methods. U.S. Pat. No. 4,372,091 uses a standard mortise and tenon interlocking key located on the arm connecting the front and rear faces. The lateral forces in a wall constructed with these modules cause very high bending stresses in the connecting arms, since the mortise and tenon keys form couples which are transmitted to the face panels. The connecting arms must also resist high vertical shear stresses caused by these couples. The bending and shear stresses so induced must be resisted respectively by heavy longitudinal reinforcing steel and by vertical steel usually in the form of strirrups. These requirements add significantly to the cost of the modules and hence to the final cost of the structure.
An object of the present invention is to provide an improvement over other prefabricated modules presently used for wall structures of this type, since the modules described in this invention are configured in such a manner as to conform more efficiently to the locations, directions and patterns of stresses induced in the wall assembly by the fill material within and by the external loads acting upon the wall. By being positioned in such a manner as to be able to accommodate more efficiently the loads imposed upon it, the stability of the assembled structure is increased. Moreover, both the intensity of the internal stresses within the module, and the physical size of the individual modules are reduced. This more effective construction results in the use of less material in the manufacture of the modules and, when used in a retaining structure, requires less excavation of soil (and consequently, less backfill material to be placed) to place the modules in the field and to complete the structure. All these factors combine to produce a much more economical structure with improved structural integrity.